Eagle attacking moa
New Zealand is unique in the world in that it has no native land mammals (apart from 3 species of bat) but has/had a prolific bird life. It was home to the moa, the worlds largest bird which weighed up to 180kg, the worlds largest eagle weighing 15kgs (but with a short wingspan and tremendously strong flight muscles to manouvre amongst tall forests) and many more flightless birds such as the iconic kiwi. Flightless because most of the food was on the ground and with no land predators why fly? Then man came 1000 years ago in the form of the Maori people and brought with them rats and dogs. The rats competed for food and dogs and man killed and ate many species into extinction. The moa, developed over millions of years, was thought to have disappeared in a century. The kakapo, the worlds only flightless parrot, is also one of it's most endangered bird species (after careful breeding by the conservation dept. there are 62 left), it's only defence (from the eagle) was to freeze which made easy pickings. So the moa went and so too did the eagle with no large prey left.
Over time the Maori people developed stratagies to preserve species but then the Europeans came with Cook in 1769 and it started all over again.
The small outer islands provided some protection for species such as the tuatara, known to be 220 million years old, and now are predator free sanctuaries as we try to atone for the damage we have wreaked.